The present invention relates generally to the recovery of evaporative emissions for a vehicle. More specifically, the present invention relates to a method and apparatus including a microgenerator or an array of microgenerators to recover evaporative emissions from vehicle fuel tank to generate power.
In today""s automotive market, vehicles are typically equipped with a fuel evaporation control system to eliminate evaporative emissions from a fuel tank to the environment. The evaporative emissions are collected in a purge canister such as a charcoal canister where carbon granules store the vapor when the engine in the vehicle is turned off. After the engine has been started, the canister will be regenerated and the vapors will enter the engine to be used in normal operation. If a vehicle is left unused for an extended period of time, the canister may saturate with fuel, and vapors may be released into the atmosphere. An extended period of disuse of the vehicle will also affect the electrical system, specifically the battery. Parasitic currents are drawn from the battery when the vehicle is off to maintain memory in various electronic devices, through the polling of wireless communication services, and the battery is also naturally discharging through internal battery parasitic currents. The battery after this extended period of disuse may expend all of its electrical energy and fail to start the vehicle when desired by an operator.
The present invention includes a method and apparatus that uses a microgenerator or array of microgenerators to utilize fuel stored in a canister supplemented by fuel from the vehicles fuel system to charge the battery in a vehicle. During extended periods of vehicle disuse, this will prevent the canister from being saturated and the battery from discharging. Formerly wasted fuel vapors discharged to the atmosphere are now used to charge the battery.
A microgenerator comprises a gas turbine supplied with fuel and air that rotates a generator to produce electrical power. The microgenerator may further include AC/DC and DC/AC converters to condition the power as needed. The microgenerator will have dimensions of substantially under one inch in area and one-tenth of an inch in volume, but any other dimensions are within the scope of the present invention including larger and smaller dimensions. Microgenerators may be arrayed in series or parallel, depending on the required voltage and current outputs. Alternatively, a microgenerator may consist of a fuel cell supplied with fuel and air.
The present invention further includes a method and apparatus to determine the state of charge (SOC) of a battery in a vehicle. The SOC is defined as the percentage of the full capacity of a battery that is still available for further discharge. The SOC determination is used by the microgenerator(s) to regulate the charging of the battery.